1. Field of the Invention
The present invention relates to structural boards used for floors, and in particular, an improved tongue and groove board having a drainage system incorporated into the tongue and groove elements.
2. Description of Related Art
Tongue and groove (T&G) structural boards are well known in the construction industry. They are typically made from plywood, particle board, wafer board, strand board, or other composite wood product materials. Tongue and groove boards are particularly well suited for installation on a joist framing assembly to form a structural sub-floor. T&G boards serve especially well as sub-flooring because of their interlocking edges which reduce vertical offset between adjacent boards resulting in a smoother floor. In addition, the interconnected edges prevent relative movement between adjacent edges as persons walk on the floor, thereby reducing squeaking in the floor. Typically carpet, tile or a hardwood is installed over the structural sub-floor to provide the finished floor surface.
U.S. Pat. No. 4,807,416 to Parasin and U.S. Pat. No. 4,095,913 to Pettersson et al disclose tongue and groove boards incorporating particular tongue and groove shapes and features designed to reduce stresses generated by water absorption along the interconnected edges of adjacent T&G boards, and thereby reduce buckling. However, no provision is made for a means to reduce or prevent the accumulation of water on the upper surface of the sub-floor.
U.S. Pat. No. 2,031,596 to Fulbright discloses tongue and groove boards held together by an embedded spring to form a floor block assembly. U.S. Pat. No. 432,245 to Megis discloses a lumber strip for installation over a sub-floor to form a finished floor surface which incorporates vertical channels spaced along the tongued edge of the strip. The channels are cut into the upper surface of the strip to accommodated blind nailing of the strip to the sub-floor.
U.S. Pat. No. 576,569 to Gemmer and U.S. Pat. No. 3,740,909 to Stinnes disclose wall boards incorporating interlocking grooves to provide a weather tight seal between adjacent boards.
While T&G boards are generally very useful in this application, they are subject to damage if water accumulates on the sub-floor surface during the construction of the building. Water often accumulates in small pools on the assembled sub-floor when rain or snow falls before the building is completed. The result is that the boards may buckle along their edges as the boards and the interlocking edges swell from water absorption.
U.S. Pat. Nos. 5,182,892 and 5,335,473 to Chase disclose a tongue and groove board having notches cut in the tongue portion of the board to provide drainage to prevent the accumulation of water on the boards. However, since the notches are on the tongue portion of the board, only narrow channels along the top and bottom edges of the board are available for allowing the water to drain to and from the notches. Such an arrangement can still cause water damage problems because the water is not able to drain quickly.
A need therefore exists for a T&G board for use in assembling a sub-floor assembly which allows water to quickly drain from the upper surface of the sub-floor, and which is economical to produce.